ACE is a proteolytic enzyme which plays an important role in the regulation of a blood pressure and amounts of body fluids, and has activity of converting angiotensin I into angiotensin II having strong hypertensive activity, in the rennin-angiotensin system which controls the blood pressure increase. Various studies have been carried out on the inhibitors of this enzyme, and it is known that they have activity of decreasing blood pressure (D. W. Cushman et al., Biochemical Pharmacology, Vol. 20, Pages 1637-1648 (1971), Robert J. L. et al., The Journal of Pharmacology and Experimental Therapeutics, Vol. 204, Pages 281-288 (1977)). Regarding the ACE inhibitors, various pharmaceutical agents have been studied and are commercially available (Yoshihiro Kaneko et al., “Igaku no Ayumi” (Progress in Medical Science), vol. 122, pages 62-85, 1972; Toshio Hisayoshi et al., “Hitome de Wakaru Koketsuatsu” (Hypertension Recognizable at a Glance), 2nd edition, pages 54-55, 1998; Noboru Toda et al., “Jyunkankei Chiryoyaku no Sayo Mekanizumu” (Action Mechanism of Circulating system Therapeutic Agents), pages 260-265, 1998). In addition, peptides capable of inhibiting ACE have been found from casein and various foods such as gelatin, sardine and bonito. For example, casein-derived peptide VPP (Val-Pro-Pro, IC50:9 μM), casein-derived peptide IPP (Ile-Pro-Pro, IC50:5 μM) and casein-derived peptide VAP (Val-Ala-Pro, IC50:2 μM) and corn protein α-zein-derived LQP (Leu-Gln-Pro, IC50: 2 μM) are known (Yasunori Nakamura et al., Journal of Dairy Science, Vol. 78, Pages 777-783 (1995); Shinsuke Miyoshi et al., Agricultural and Biological Chemistry, Vol. 55 (5), Pages 1313-1318 (1991); Susumu Maruyama et al., Agricultural and Biological Chemistry, Vol. 51 (6), Pages 1581-1586 (1987)).